Little is known about the role of medications in predicting suicide-related outcomes and unintended death in older Veterans. Veterans 50 years and older have the highest number of lives lost to suicide, make up the majority (> 70%) of the Veteran population, and are highly likely to experience conditions (e.g., chronic pain, sleep disorders, musculoskeletal) associated with commonly prescribed medications that are potential markers for suicide risk (hereafter referred to as ?high-risk? drug categories, including benzodiazepines, sedative- hypnotics, opioids, antidepressants, and antiepileptics). The role of these medications in relationship to risk of suicide and unintended death in older Veterans is likely complex and, yet, extremely informative. Simply access to ?high-risk? medications, similar to access to firearms, may increase risk. Moreover, medications may be causally linked where central nervous system-acting medications increase vulnerability to risk of attempting suicide. In addition, the type and amount of medication use can serve as a valuable marker of the presence and severity of psychiatric symptoms and associated emotional and mental distress, in ways that diagnostic codes alone are unable to capture. It is also likely that polypharmacy is an important indicator of a complex of comorbidities that increases risk of suicide. All-in-all there are multiple potential pathways where medications may be strongly associated with suicide risk in ways not fully captured by other predictors. Thus, information on medication use could substantially enhance our ability to identify older Veterans at high risk of suicide, above and beyond known risk factors such as the presence of psychiatric diagnoses. This could provide extremely valuable products by giving us tools to better identify high-risk Veterans, who could then be targeted for enhanced screening and early intervention to prevent suicide. With mounting concern regarding misclassification of suicides as accidental deaths by drug overdose, better understanding the impact of medications on death by unintentional injury is also important to informing suicide prevention efforts. Furthermore, examining associations by such factors as age, gender, race/ethnicity, homelessness, Vietnam Veteran status, service connected disability, posttraumatic stress disorder, and traumatic brain injury supports the Department of Veterans Affairs' mission to meet the needs of these vulnerable groups. To this end, the primary goal of our study is to determine the role of medications as prognostic factors, above and beyond other factors, in predicting risk of suicide and unintended death in older Veterans. We propose in this current application to add new questions on medication prescribing and use to an existing CSR&D Merit Award project (CX001119; PI: Byers), which has formed a unique cohort for late-life suicide research. This cohort includes all Veterans (~5,000,000) who used VA health care services, were initially 50 years and older in fiscal year 2012- 2013, and followed to present. This cohort includes information on all psychiatric and medical diagnoses and death by suicide and unintentional injury and suicide attempt. We propose linking multiple National Pharmacy databases (i.e., VA and Medicare) to this cohort ? to study medications as a prognostic factor in predicting suicide-related outcomes and unintended death. In doing this, we will characterize the use of ?high-risk? medications and polypharmacy prior to suicide-related outcomes and unintended death among older Veterans (Aim 1), determine whether use, and certain patterns of use, of ?high-risk? medications (Aim 2) and polypharmacy (Aim 3) provide additional prognostic value above and beyond other predictors, and assess differences of associations by vulnerable groups (Aim 4). If this hypothesis is true that certain medications and patterns of use can identify older Veterans at increased risk of suicide and unintended death, it has important implications for clinical care. The use and initiation of medications could be utilized to target risk assessments and prevention programs for older Veterans at high risk. This is something the VA is uniquely positioned to do.